clone machine...roots not taking????

any tricks i can do to get these clones to take root, 3 out of 10 rooted. ph water,and little bit super thrive

cut the stem at a 45 degree angle, and other then superthrive, ive heard cut the leaf tips back about 1/2 length... and some nutrient with high Phosphorus.
ive also heard pure water so the roots have to grow...
ive heard foliar feed like a mofo
ive heard keep them warm
guess everyone does it differently. good luck